Method of covering cores



June 1 ,1926. 1,586,811

A. R. KEMP METHOD OF COVERING CORES Filed April 30, 1925 Patented June1, 1926. i

UNITED STATES PATENT OFFICE.

ARCHIE R. KEMP, F TOWACO, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COM-PANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

METHOD OF COVERING CORES.

Application filed April 30, 1923. Serial No. 635,542.

This invention .relates to methods of c0vering cores and moreparticularly to the covering of cores with vulcanizable plasticmaterial.

When two lengths of a core, such as an electric conductor which isinsulated with a vulcanized sheathing, are spliced together to provide amechanically and electrically continuous core, it is necessary that thesplice be provided with an insulating covering comparable with that overthe remainder of the core. Also it is sometimes necessary to cover aportion of such a core which may become exposed, due to the removal ofthe associated vulcanized sheathing, with a similar covering. Since insuch cases the covering must be vulcanized to agree with and to unitewith the insulation of the remainder of the core, it is desirable thatthe covering be readily adhesive and be of such a character that it maybe vulcanized within a short period without deleteriously afiecting thepreviously vulcanized sheathing ad acent" thereto.

An object of this invention is to cover a core with plastic material.

A further object is to expel air from the surface of the core whilecovering it with a plastic coating. Another object is to cover a corewith a non-porous vulcanized coating. An additional object is to coveran exposed portion of a sheathed core, such as that occurring at asplice therein, with a coating homogeneously united with and havingcharacteristics similar'to the vulcanized coating on the remainder ofthe core.

It is believed that the invention will be clearly understood from thefollowing description and the accompan ing drawings relating to oneembodiment o theapparatus by means of which the process may hepracticed.

' In the drawings,

Fig. 1 shows an end elevation of a preferred form of vulcanizingapparatus particularly adapted to be used in connection with thevulcanizing of material covering a splice in a core, or an exposedportion of a core;

Fig. 2 is a fragmentary view, in section, of such apparatus containing aspliced core and the assoc ated portions of covering material prior tothe operation of the apparatus. Fig. 3 is a similar view, showing thecondition existing while the covering is being vulcanized;

Fig. 4 shows an end-wise sectional view.

along the linesA-i of Fig.2, and

Figs. 5 t0 8 inclusive show successive stages in the-application of apreliminary coating to one particular type of core to which theinvention is especially adapted.

Referring to the drawings, a base 10 supports a fixed lower mold portion11 adapted to co-operate with a movable upper mold portion 12, thelatter portion being movable toward or away from the former portion bymeans of a suitable operating rod 13 suitably mounted in a projectinglug of a sleeve -or lowers the member 17 along the post 15 and the uppermold portion 12 mounted therein is moved toward or away from the lowerportion 11, dependent upon the direction of rotation of the sleeve.

The mold portions 11 and 12 are provided with centrally locatedsubstantially semicircular depressions 18 and'19, extending throughouttheir length for receiving cylindrical portions 21 and 22 respectivelyof plastic material to be used in covering the exposed portion of thecore. Near the ends of the depressions annular flanges 23 and 24, theedges of which when the two mold portions are in their closedposition,leave an opening having the same diameter as the sheathed core. Theseannular projections prevent the free extrusion of the plastic materialout of the ends of the mold, over the surface of the sheathed core.Lengthwise channels 25 are provided on either side of the depressions 18and 19 for receiving the surplus plastic material as the upper moldportion is advanced to its closed position. Each of the mold portions 11and 12 is provided with some suitable heating means, such as anelectrical resistance unit which may be connected with any suitablesource of current by pairs of conductors 40 and 41 respectively so thatthe temperatures of the portions may be selectively controlled.

Referring particularly to Figs. 5 to 8 inclusive a metallic core 30 isshown which may be composed of a large electrical conductor surrounded ba plurality of smaller conductors and to wl i 3.1 of adhesive materialmay be applied to the cores prior to the application thereto of theplastic joining material.

Although it is to be understood that the invention is not to be limitedin any manner thereby, the process will be described in detail as beingemployed in connection with.

the covering of, a splice in an insulated electrical conductor of thegeneral type disclosed in the co-pending application of Robert R.Williams, Serial No. 674,161, filed November 12, 1923, to which theprocess and the apparatus disclosed is particularly adapted.

In the manufacture of such an insulated conductor, a thin layer ofsubstantially pure gum rubber is formed around the composite conductorand plastic vulcanizable material, which may be of the type disclosedand claimed in the co-pending application of A. R. Kemp, Serial No.521,032, filed December 8, 1921, is then formed over the rubber and thecore sheathing is vulcanized in any suitable manner. When it is desiredto cover a spline in, or an otherwise exposed portion of, such aconductor, it is necessary to employ a material which may be quicklyapplied, which closely adheres to the core and the adjacent coveringprior to its vulcanization, which may be quickly vulcanized and therebythorou hly united with the previously vulcanize covering of the coreadjacent the exposed portion without producing any deleterious effectsand furthermore which provides a covering possessing substantially thesame characteristics as that over the remainder of the core length.

A material of this type which possesses all of these characteristics isdisclosed and claimed in the co-pending application of A. R. Kemp SerialNo. 673,822, filed November 9, 1923, and consists essentially of thefollowing ingredients and in the proportions named:

Per cent. Rubber (3) 40 Zinc oxide 35 Iiitharge 20 Sulphur 4 Parafline 1having a width in excess of the circuinten ence of the spliced core isplaced in a horiich a plastic sheathing.

"extruded over the core.

zontal position underneath and in tangential contact with the core 30 asshown in Fig; 5. Care is taken to insure that the line of contact alongthe underside of the core is continuous, after which the portions of thesheet Tm on either side of such line-of contact are pressed upwardlyagainst the circumference of the core, gradually working around the corein the successive positions shown in Figs. 6 and 7. In this manner allair is expelled from the surface of the metallic core preceding thecontact of a portion of the sheet with the corresponding portion of thecore. lVhen thesheet assumes the position shown in Fig. 7 the core iscompletely encased with a rubber film in very much the same manner as itwould be if rubber were The excess sheet is then cut away and the endsfolded down as shown in Fig. 8.

The cylindrical portion 21 of the jointing compound is then prepared bycutting away a portion of each end of the cylinder so that the endsconform to the tapered portions of the vulcanized material adjacent thespliced portion of the core. The lower mold portion 11 is then heatedslightly and the cylinder of compound is placed in the depression 18,care being taken to insure that intimate contact is made between thesurfaces of the depression and the jointing compound. The upper moldportion 12 is then lowered to its closed position over the lower portion11 and both mold portions are heated for three or four minutes to atemperature between 200 and 220 F.', this rendering the cylinder 21 moreadhesive and sufficiently plastic that it will flow readily upon theapplication of pressure thereto. In the meantime the portion 22 issimilarly prepared and heated, externally of the mold, by a gas flame orby some other suitable means. Also the tapered ends of the vulcanizedcovering over the core adjacent the splices have been rubbed with someof the plastic jointing compound to remove any'loose particles of thevulcanized sheathing as well as to fill the cavities or depressions inthe tapered surfaces with the compound. The upper portion of the mold 12is then raised and the spliced core is placed longitudinally above andin tangential contact with the portion 21'. The heated portion 22 ofjointing compound is similarly placed on top of the core. In each casecontact is first established between the mid points of the cylinder ofjointing compound and of the exposed surface of the core, and the lineof contact is then extended in each direction until it'reaches the endof the two to three minutes. Due to the tangential line of contactbetween the cylinders of comtapered vulcanized coating in each direction4 around the circumference of and expelling all air from the coresurface. When the approaching"films" of 'jointing compound meet, thecore is thoroughly surrounded by the jointing compound without anyinter-' vening air. As the mold 'portion'lfl descends further the excesscompound is forced outwardly into the channels 25 and from thence it mayextrude. at the end of the mold. The temperature ofthe molds is thenincreased to approximately 300 and retained at such. a temperature for aperiod of approximately twenty minutes. Thereafter the upper portion 12is raised and the core and theassociated splice is removed from theapparatus, after which'the sheathing is rapidly cooled by sponging withcold water.

By the. complete expulsion of air from the core before the applicationof-the jointing compound there is no tendency to intro duce bubbles intothe compound during vulcanization and as a result a substantiallynon-porous sheathing is obtained.

It willbe evident that the process may be employed in continuouslycovering a moving core in which case the continuous'cyhnders ofvulcanizableinaterial may be ex truded adjacent and parallel to themoving core or applied thereto in some other manner and the core withthe associated cylinders passed through. suitable molds adapted. tospreadithe material over the surface of the core and to thereaftervulcanize such material.

What is claimed is:

'1. The method of extending a vulcanized sheathing over a core whichconsists in placing a batch of plastic material in tangential. contactwith the core and the sheathing and completely spreading the materialfrom -such' contact over and expelling air from the surface of the core.t

2. Thev method of extending a vulcanized sheathing overa oore whichconsistsein placing a plurality of separated batches of such material intangential contact with the core and the sheathing, and applyingpressure to the batches to cause the material thereof to spreadcompletely over and exclude air from the surface of the core.

3. The method of extending a vulcanized sheathing over a core whichcomprises applying. plastic material laterally to the core and thesheathing, spreading the material sidewise over the core so as to expelair from the surface of the core, and subsequently vulcanizing thematerial.

4. The method of extending a vulcanized sheathing over a core, whichconsists in placing a plurality ofseparated rods of plastic I materialin tangential contact with the core and the sheathing, and applyingpressure to the -ortidns, causing the material thereof to completelycover the core.

I). The method of covering a core with plastic material, which consistsin placing a plurality of separated cylindrical portions of suchmaterial in tangential contact with the core, and applying pressure tothe cylindrical portions at points diametrically opposite to the line ofcontact between the cylinders and the core, causing the plastic materialto flow equally from each contact line around the core and expelling allatmosphere from the core surface between the" approaching walls ofplastic material.

6. The method of extending a vulcanized sheathing over a core whichcomprises ap-- plying plastic material to one sideof the core, heatingthe material to. increase its plasticity, applying pressure to thewarmed material tocause it to flow toward the op posite side of thecore, and subsequently vulcanizing the material.

7 The method of covering a core, which consists in placing a pluralityof separated batches of vulcaniz'able material in tangential contactwith the core, simultaneously applying pressure to the batches to causethe material thereof to spread equally from the tangential contacts overand to exclude air from the surface of the core, thereby completelycovering the core with intimately contacting plastic material, and thenvulcanizing the material.

8. The method of coating a core with vulcanizable material, whichconsists in placing a batch of plastic vulcanizable material in a moldportion, heating the mold por-- tion to increase the plasticity of thematerial, placing a core in tangential contact with the batch, placinganother batch of the plastic material in another mold portion, causingthe two portions to approach each other to spread the plastic materialover and expel air from the surface of the core and heating both of theportions to vulcanize the material on the core.

9. The method of extending a vulcanized sheathing over an exposedportion of a core,

-which consists in placing a plurality ,of

spaced batches of vulcanizable plastic material 1n tangential contactwith the core, ap-

plying pressure to the batches to spread the material thereof completelyover and expel air from the-surface of the core and the;

end of the vulcanized sheathing, and then vulcanizing the material tothoroughly secureit to the core and to the previously vulcanizedsheathing.

10. The method of coating :1 core with vulcanized material, whichconsists in placing a rod shaped portion of such material parallel toand in tangential contact with the core, applying pressure to the rodshaped portion to spread the material thereof over and expel air fromthe surface of the core and Vulcanizing the material.

11. The method of coating a core with vulcanized material, whichconsists in placing a plurality of separated cylindrical portions ofvulcanizahle material parallel to and in tangential contact with thecore, applying pressure to the portions to spread the material thereofover and expel air from the surface of the core, shaping the portionsand vulcanizing the portions.

12. The method of coating a splice in a Vulcanized covered core, whichconsists in tapering the vulcanized covering on either side of thesplice, forming the ends of a plurality of cylindrical portions ofplastic material to conform to the tapered portions, placing theportions in tangential contact with the splice and in contact with thetapered portions, applying pressure to the cylindrical portions, causingthe material to spread over and expel air from the surface of the coreand the tapered portions, and vulcanizing the material.

13. The method of extending a vulcanized sheathing over an exposedportion of a core, Which consists in rubbing the vulcanized sheathingadjacent the exposed core with plastic vulcanizable material to removeloose particles of vulcanized sheathing and foreign matter from and tocoat depressions in the sheathing with the material, placing a portionof the plastic material in contact with the prepared sheathing, andvulcanizing the material to thoroughly unite it with the yulcanizedsheathing.

In witness whereof, I hereunto subscribe my name this 19th day of AprilA. 1)., 1923.

ARCHIE n. KEMP.

